The present invention pertains generally to vehicles which must be guided in a precise manner at a delivery or work site by an operator located at other than the driver's station.
In the delivery of earthen materials such as aggregate, sand and gravel, it is often highly desirable to distribute the load along a path or course and at a desired depth to avoid doing same later by costly manual labor. Construction sites however often include irregular terrain which greatly hinders vehicle maneuvering during delivery. This, coupled with the fact that tight quarters are frequently encountered, makes it highly desirable to have the vehicle driver out of the truck cab and stationed where he can best observe discharging of material. Such delivery is still further complicated by the amount and heavy nature of the earthen material being delivered which necessitates the vehicle be of considerable size and weight. Known systems for such delivery operations have been proposed where the driver/operator is stationed out of and usually at the rear of the vehicle. The difficult conditions encountered at work sites, including uneven terrain, imparts severe loads on the vehicle driveline and presents some risk of a runaway vehicle or, at least, hinders uniform discharge of material along a course.
In the prior art is U.S. Pat. No. 5,190,118 which discloses a system directed toward delivering aggregate from a truck with the driver relocated at the rear of the vehicle. The differential requires, in effect, two drive shafts, one powered by the truck engine and the second powered by a hydraulic motor with a steering system also utilizing a hydraulic motor all controlled by an operator stationed at the truck rear end.
U.S. Pat. No. 4,318,451 discloses a truck whereat an operator may steer the vehicle from a cab or from a second cab located on a turntable equipped with a boom and shovel.
U.S. Pat. No. 4,527,656 shows a truck with a rearwardly stationed operator having controls coupled to a steering motor and to an air cylinder for shifting a gear selector.
U.S. Pat. No. 4,846,581 shows a concrete mixer truck with a rear operator station. A traverse control regulates the angle of a swash plate 36 of a pump to regulate the speed of a hydraulic motor 38 which drives a PTO engageable with the vehicle transmission. A remote steering system utilizes an assist cylinder coupled to a steering arm of the truck. Some braking action occurs through control of a pump swash plate.
The known prior systems do not address the problem of providing precise speed and steering controls nor the problems encountered when coupling and uncoupling a hydraulic motor from a vehicle driveline. Heretofore the known prior art systems do not provide means for imparting auxiliary system torque to a vehicle driveline and subsequently terminating same without risk of damage to components.